1. Field of the Invention
The present invention relates generally to containers which store various kinds of cargo therein and are transported by ships or the like and, more particularly, to a folding container which is configured such that a small number of workers can easily fold or unfold a container body using a folding means so that it is convenient to handle the container and the use of space is optimized, and which has a superior durability and is able to be safely used, because the container body can be reliably maintained in the folded or unfolded state.
2. Description of the Related Art
Generally, containers are used to transport various kinds of cargo by ships or the like, for example when exporting or importing for trade purposes.
In the conventional art, such a container has a rectangular box shape.
In the case of the conventional container, even when it contains nothing, the empty container must be transported in the shape of a rectangular box. Therefore, the rate of use of space is low, thus increasing distribution costs.
To overcome the above problems, several folding containers have been proposed that can be stored and transported in the folded state when empty.
Particularly, in Korean Patent Registration No. 10-638570 which was filed by the applicant of the present invention, a folding container includes a container body which defines a loading space therein. The container body includes a top plate, a bottom plate, left and right side plates, and front and rear end plates. The left and right side plates are vertically provided at opposite sides between the top plate and the bottom plate. Each of the left and right side plates includes upper and lower plate bodies. The upper and lower plate bodies of the left and right side plates are connected to each other and to the top and bottom plates in the longitudinal direction of the container by spring hinges which are provided on an outer portion between the upper and lower plate bodies and on inner portions of upper and lower ends of the upper and lower plate bodies. Thereby, the upper and lower plate bodies can be folded inwards in such a way to face each other. The front and rear end plates are respectively coupled to the front and rear edges of the bottom plate by bottom hinges so as to be rotatable and foldable inwards or outwards. Furthermore, the top plate and the upper plate bodies of the left and right side plates, the bottom plate and the lower plate bodies of the left and right side plates, and the top plate and the front and rear end plates are locked to or unlocked from each other by catch clamps. Each catch clamp includes a clamp part and a latch which are respectively disposed at corresponding positions facing each other. The clamp part includes a locking hook which is provided so as to be rotatable around a shaft so that the locking hook is releasably locked to the latch.
In the technique disclosed in the registered patent mentioned above, when the container body contains nothing, the front and rear end plates of the container body can be folded inwards and the upper and lower plate bodies of the left and right side plates can be folded inwards in such a way as to face to each other. The container body is stored and transported in this state thus enhancing a rate of use of space, and thereby reducing distribution costs.
However, this technique developed by the applicant of the present invention has the following problems.
First, to elastically unfold the upper and lower plate bodies of the left and right side plates of the container body which have been in the folded state, the elastic force of the spring hinges must be sufficiently high. However, when the elastic force of the spring hinges is high, it becomes very difficult to fold the upper and lower plate bodies of the left and right side plates due to the high elastic force of the spring hinges.
In particular, because the folding operation is manually performed by workers, it is very difficult for a small number of workers to fold the container body, thus increasing safety concerns.
Secondly, the top plate, the left and right side plates and the bottom plate of the container body are connected and fastened to each other only by spring hinges. Considering the fact that corner castings provided on the respective corners of the top plate are held, lifted and moved by a container handling machine, the durability of the container body is reduced with respect to the vertical or horizontal direction.
Particularly, the spring hinges have the same structure, and each spring hinge has only one torsion coil spring. Thus, the elastic force of each spring hinge is not sufficient. Therefore, a comparatively large number of spring hinges are required to smoothly unfold the container body. Furthermore, the springs hinges that rotate to 90° and are installed between the top plate and the upper plate bodies of the left and right side plates and between the bottom plate and the lower plate bodies of the left and right side plates have the same structure as that of the spring hinges that rotate to 180° and are installed between the upper and lower plate bodies of the left and right side plates. Thus, a portion where the elastic durability of the torsion spring of the spring hinge weakens may occur.
Third, in each spring hinge, the legs of each torsion coil spring protrude upwards and downwards from the surface of the spring hinge body. Thus, to prevent the legs from interfering with other elements, grooves are formed in upper and lower portions of the spring hinge body, and the legs of the torsion coil spring are seated into the corresponding grooves. However, because the torsion coil spring is twisted when the container body is folded, the legs of the torsion coil spring must move in the longitudinal direction of the spring, but the legs of the torsion coil spring cannot move. Thus, a load applied to the torsion coil spring is increased, thus reducing the durability of the spring hinge.
Fourth, after the top plate, the left and right side plates and the bottom plate of the container body are folded, and double locking hooks of the catch clamps that are disposed on the bottom plate are locked to latches of the corresponding catch clamps that are disposed on the top plate, thus maintaining the container body in the folded state. In this state, when unlocking the double locking hooks to unfold the container body, because the top plate and the left and right side plates are elastically biased upwards by the elastic force of the spring hinges, it is very difficult to remove the double locking hooks from the latches.
Fifth, the double locking hook of each catch clamp comprises two typical locking hooks which are connected to each other. The double locking hook is elastically biased upwards by the elastic force of a coil spring to prevent the double locking hook from hanging down to come into contact with the ground. Rather, the double locking hook may be bent and inserted between the left and right side plates, thus impeding the folding of the container body.
Sixth, when a first one of the left and right side plates of the container body which has been folded is unfolded after a second one of them is vertically unfolded, the second side plate may be bent towards the first side plate rather than being maintained in the vertical state, and the first side plate and the top plate may lean towards a worker, thus endangering the safety of the worker.
Seventh, the top plate, the left and right side plates, and the bottom plate of the container body slope relative to each other at predetermined angles to prevent rainwater from entering the container body. However, because the junctions between the top plate, the left and right side plates and the bottom plate of the container body have no sealing structure, the ability to seal the container body is markedly low.
To solve the above-mentioned problems, the applicant of the present invention worked hard to apply various improvements to the defective parts of the conventional technique developed by the applicant of the present invention and thus developed a folding container whose quality has been enhanced.